Stereoscopic adapter



Jan. 24, 1950 J. M. RICHARDS 2,495,288

STEREOSCOPIC ADAPTER Filed Deo. 15, 1945 8 Sheetsfsheet 1 1H- 'in-S E5 ,J f l WSW :53x WHL 1 3B L SGI V FJ a5 LM "5 0 Il- `z [u '+3 'uur LLLlH rmw [l l I \O 'G as 73u hf Ljs? E8 "Bnk- 5@ 1+ wo BS; lil 38V 1w IIII 25 355, U25 U'll J 56 353 5T: lll l [l +9- |l Llo 'en I a@ 11,1 uw 1 WI 212- 51a.`

Wwf n INVENTOR.

JOHN MARK R|cHAR os Jan- 24, `1950 .1. M. RICHARDS u 2,495,288

sTEREosCoPIc ADAPTER 4 Filed Dec. 15, 1945 8 Sheets-Sheet 2 A BOB 33 F- TEJQ El 9 INVENToR.

vJOHN MARK RICHARDS BY l fi, Q

Jan. 24, 1950 J. M. RICHARDS 2,495,288

sTEREoscoPIc ADAPTER Filed Deo. 15, 1945 s sheets-sheet s INVENTOR. JOHN. MARK RICHARDS Jan. 24, 1950 1. M. RICHARDS 2,495,288

STEREOSCOPIC ADAPTER Filed Dec. 15, 1945 l y 8 Sheets-Sheet 4 INVENTOR. JOHN MARK RICHARDS BY Jan. 24, 1950 .1lt M. RlcHARDs 2,495,288

STEREOSCOPIC ADAPTER Filed Dec. 15, 1945 v 8 Sheets-Sheet 5 INVENTOR. JOHN MARK RICHARDS .Af/Wifi Jan. 24, 1950 r J. M. RICHARDS 2,495,288

STEREOSCOPIC ADAPTER Filed Dec. 15, 1945 8 Sheets-Sheet 6 -Jan.r 24, v1950 J. M. RICHARDS 2,495,288

STEREOSCOPIC ADAPTER Filed Dec. 15, 1945 8 Sheets-Sheet '7 INVENTOR. JOHN MARK RICHARDS Jan. 24, 1950 Filed Dec. 15, 1945 J. M. RICHARDS STEREOSCOPIC ADAPTER 8 Sheets-Sheet 8 IBG INVENTOR.

JOHN MARK RHARDs BY Patented Jan. 24. 1950 UNITED STATES PATENT OFFICE STEREOSCOPIC ADAPTER John Mark Richards, New York, N. Y.

Application December 15, 1945, Serial No. 635,276

Claims. l

This invention relates to new and useful improvements in a stereoscopic adapter.

An object of this invention is to produce stereoscopic images accurately and easily with all types of single aperture cameras.

At this point certain definitions of terms to be used in the following description are given to enhance the clarity of this description of the stereoscopic adapter of the present invention:

1. The camera lens total angle of view is a composite angle pyramidal in form with a rectangular base consistent in proportions with the two dimensions of the camera image eld subtending their respective angles to the optical center of that camera lens system.

a. The camera lens horizontal angle of View is one-half the angle subtended by the longer of the two dimensions of an image area provided by a particular camera image field to its lens optical center. In other words it is usually the angle subtended by the short dimension of one of a pair of stereoscopic images to that particular lens at its focal length.

b. The camera lens vertical angle of View is the angle subtended by the shorter of the two dimensions of an image area provided by a particular camera image eld to its lens optical center.

2. The stereoscopic base is that distance separating the two lateral stereoscopic adapter mirrors. (This is obtained by the relative placing of the lateral housings which contain, rotatably mounted, the lateral mirrors.)

3. The stereoscopic angle is the angle subtended by the stereoscopic base to the object distance which perpendicularly bisects this base. This angle forms at the object a point of stereoscopic convergence which is included on the optical axis of the lens in the anterior conjugate focal piane of the lens.

4. The optical axis of the Icamera lens is similar to that of all lenses. The said optical axis is horizontal and it is in relation to it that certain terms of position and direction are used:

a. Anterior means parallel to the optical axis and facing away from the camera lens.

b. Posterior means parallel to the optical axis and facing the camera lens.

c. Medial means perpendicular to the optical axis and facing the axis horizontally.

d. Lateral means perpendicular to the optical axis and facing horizontally away from the axis.

e. Superior means perpendicular to the optical axis in a vertical direction towards the observers head (observer is the person taking the picture).

f. Inferior means perpendicular to the optical axis in a vertical direction away from the observers head.

5. The anterior conjugate focal plane of the lens is the plane of the object perpendicular to the optical axis, in its position relative to the lens for a given image position.

6. The posterior conjugate focal plane of the lens is the plane of the image perpendicular to the optical axis, in its position relative to the lens for a given object position.

More particularly the object of this invention is to make variable conjointly or disjointly, as desired, all the optical elements of stereoscopic picture taking, namely:

l. Camera lens focusing,

2. Camera lens aperture,

3. stereoscopic base,

4. stereoscopic angle,

5. Object range finding,

6. Object viewing.

These above mentioned factors are provided with means of synchronization with the range finder such that visual use of the object range nder system provides accurate stereoscopic picture taking, with the above elements in various combinations, accordingly to achieve certain effects, as desired.

Certain other variables associated with the above mentioned elements are provided with means for adjustment. Among these are:

1. Axially centering the camera lens with the stereoscopic adapter.

2. Adjusting for the camera lens angle of view by an equal angular adjustment of the center range-finder mirrors and the lateral mirrors, for each respective side, to the optical axis.

3. Medial masking of the anterior apertures of the lateral housings.

4. Variable masking of the observers field of view.

5. Focusing of the viewer lens system variably.

In general, there are three separate mirror housing units, a central one and two lateral ones. These housings are maintained at variable stages of separation (stereoscopic base) by a means for simultaneously adjusting the two lateral or side housings towards or away from the central housing.

The central housing is stationary relative to the camera lens and has a posterior central aperture for engaging upon a camera lens in axial alignment. Two center mirrors with planes at right angles to each other with their reflecting surfaces directed posteriorly and laterally in the optical axis of the camera lens, and fixedly mounted within said central housing, are a1'- ranged with their contacting edges extended vertically.

The said two center mirrors with planes at right angles to each other and with their refleeting surfaces directed posteriorly and laterally, and nxedly mounted within said central housings and set with their contacting edges extending vertically, can be in either of two arrangements:

1. The iirst arrangement is one in which the mirrors are set laterally relatively and the contacting edges of the mirrors extends vertically through the optical axis of the camera lens, and the mirrors are both wholly reiiecting. rlhis is the preferred type of arrangement.

2. The second arrangement is that one in which the mirrors are set in sequence anteroposteriorly in the optical axis of the camera lens, similarly to the preferred type of center range iinder mirrors later described. And also similarly to said preferred center range-lnder mirrors, the anterior-more mirror would be fully reiiecting and the posterior-more one would be equally reflecting and equally transmitting. In this fashion these mirrors would Vfunction similarly to those of the iirst arrangement, but their contacting edges would extend vertically laterally to the optical axis of the camera lens.

The central stationary housing also contains the center optical elements of an object rangeiinder system, and an object Viewing system arranged to coincide in their extended optical axes with that of the camera lens.

The central stationary housing has anterior and superior apertures for viewing and 'two lateral ones for stereoscopic picture taking and for use of the range-nder system.

The two side housings are reversely identical, that is, are mirror images of each other. The side housings are disposed laterally to the central housing and have their adjacent sides open. The invention contemplates theV provision of means for separately and also simultaneously adjusting the side housings towards and away from the central housing. The side housings are provided with two sidemirrors of use both in the stereoscopic adapter camera lens system and the object range-nder system. rThese mirrors are respectively mounted vertically rotatable in each side housing, and set with their reflecting surfaces anteriorly and medially directed to the optical axis of the camera and placed with their posterior edges lateral to the more posterior edge of their respective center mirrors and forming an angle variable from a maximum of 90 to a minimum of with the optical axis oi the camera lens. Means is provided for varying the angles of the side mirrors, simultaneously preferably, but separately for special elects. The side housings have anterior apertures for the reception o rays of light from an object or objects onto their respective side mirrors. These apertures are provided with means for variable medial masking.

With the improved stereoscopic adapters preferred embodiment, briefly described above, it is possible to vary the spacing between the two side mirrors to selected distances for accommodating different degrees of stereoscopic base separation of the two lateral mirror apertures.

It is also possible to vary the angles of the two lateral side mirrors to the optical axis of the camera for varying the object range or' the picture taker and for accommodating diierent camera lens angles of view.

The two functions just described, varying the stereoscopic base, and varying the angles of the lateral mirrors provide variable stereoscopic angles.

rlhese adjustments of the stereoscopic adapter stereoscopic angle are such that variable stereoscopic depth eiects can be attained, namely:

l. Maintenance of normal relations with any lens by a depth effect proportionate to the lens magnication power.

2. Changing normal relations with any lens by:

a. Giving depth effect greater than that proportionate to the actual object distance as taken by the camera lens.

b. Giving depth less than that proportionate to the actual object distance as taken. by the camera lens.

The invention also contemplates the association of a novel viewer with the picture taker, allowing no parallax and no angle ci view variation between the cameralens total angle of view and the total angle of View of the person taking the picture.

It is also contemplated to provide the adapter with a novel object range-lnder synchronized to the stereoscopic adapter for visual adjustment of the stereoscopic images with a given camera lens without necessary reference to angleor distance scales.

It is proposed to provide a scale for synchronizing the range-finder central mirrors adjustment with eachchange in the lateral mirror angles made necessary by use of a different lens angle of View.

rOnce this adjustment is made for infinity on said two mirror pairs for a given lens horizontal angle of View (the lens focused at iniinity) it will provide accurate visual adjustment or" the stereoscopic image positions as desired superimposed, or separated preferably for that lens by simple varying or the angle of the two lateral mirrors according to the distance of an object, at that particular separation of the two lateral mirrors.

It is proposed not only to synchronize separately and simply the separation of the two side housings containing the lateral mirrors, and the rotation of the two lateral mirrors with respect to changing their angles simultaneously with the optical axis of the camera lens, but also to synchronize together these two so that as the side housings and thus the two lateral mirrors are changed in their distance apart (stereoscopic base) the two lateral mirrors will change their angles simultaneously to maintain the object originally iocused upon at that stereoscopic point of convergence. This must involve a means of knowing the exact distance :focused upon and this is most readily done through the lens focus; that is, a mechanical system is set up to change the ratio between the side housing movements, relative to each other, and the lateral mirror change or angle.

To utilize further features of this invention it is proposed to synchronize also the change of angle of the lateral mirrors due to changing distance of an object with the focusing of the lens upon that same object. This is accomplished through a mechanical system between the lens, and the lateral mirror simultaneous adjustment system.

In order to make this applicable to different lenses S distances of separation (stereoscopic bases) of the two side housings (and lateral mirrors) a mechanical system is set up for simultaneously moving the side housing system to change the ratio of movement between the lateral mirrors simultaneously with changing of angles system and the lens focusing system.

In order to allow use of said lens mirror system while the lateral housings are being actively separated in said housing mirror system, the mechanical synchronization must focus the lens only according to the stereoscopic point of convergence, and this synchronization thus must permit said housing mirror system to give its own angulation to said lateral mirrors, appropriate for said lateral housing separation and said stereoscopic point of convergence without directly changing the lens focus, while said lens mirror system is used to provide a variable stereoscopic point of convergence and an appropriate lens f focusing.

The synchronizations listed thus far allow alternate adjustment of the side housing separation-with a variable object distance, and of the lens focusing-changing object distance simultaneously angular adjustment of the two lateral mirrors system (later described as the lensmirror-housing system).

It is well to note here that when adjusting the above mechanical systems, before the lens focusing is set in gear at infinity, the central rangender mirrors and those serving as lateral rangender mirrors (preferably the two lateral mirrors of the side housings or others synchronized with them) should be set each from the angle 45 to the optical axis, closer to the optical axis by an angle equal to 1A the lens horizontal angle of view. For special close work where a practical change in the angle of view of the lens occurs, a similar readjustment must be made.

It is proposed also to synchronize simultaneously the lateral housing change of stereoscopic base and the lateral mirror rotations, such that once a given stereoscopic angle is set for by separate adjustment of the lateral housing separation and of the lens focusing-lateral mirror angle adjusting system for a given object distance, then that given stereoscopic angle is maintained for all object distances to the maximum and minimum limits of that lateral housing separation (stereoscopic base) mechanism, after which limits the synchronization to maintain the given stereoscopic angle automatically ceases and only the lens focusing-lateral mirror angle adjusting system functions, for that maximum or minimum fixed separation of the lateral housings.

There are four optical systems involved in this invention in combination and separately:

1. The simple one of the camera lens.

2. The stereoscopic adapter,

3. The range finder, and

4. The object viewer.

In the camera lens system, the lenses considered are those of all types including those of lens angle of view known as wide angle and telephoto lenses, of varying apertures and focal lengths.

In the stereoscopic adapter system there are (excluding the camera lens) four mirrors involved, in two laterally displaced mirror-image formations. The center mirrors are of proper size to accommodate the above mentioned camera lenses. The lateral mirrors are of proper size to accommodate the above mentioned camera The lateral mirrors are of vproper size to accommodate these same lenses of all different apertures and focal lengths at all desired separations of the side housings (and lateral mirrors), and at all variations of those lateral mirror angles for a given lens or a given object distance.

Housing apertures are of course arranged accordingly to accommodate these same camera lens angles and the mirror sizes laterally.

Adjustable masks for the medial sides of the anterior apertures of the lateral housings are provided. Each mask is set into the aperture to such a distance as to approximate the medial edge of the useful field of lens horizontal angle of view. This medial edge is the same for all lenses relative to the lateral mirror position of rotation and therefore must be adjustable for each rotation of the lateral mirror to keep at this edge. This is done to prevent center overlapping of stereoscopic images. Each mask is synchronized with its lateral mirrors rotation to keep at the edge of said angle of view and thus to move medially as the mirror rotates medially and laterally as the mirror rotates laterally.

No change is needed as the lateral housings separate; only as the lateral mirrors rotate. The only exception to this is one in which an initial adjustment separate from lateral mirror rotation may be made to mask some of the excessively overlapping stereoscopic image rays encountered with lenses having large apertures. The adjustment here is relative to the lens aperture, after which setting, the previously described synchronization of the lateral mirror rotation to the mask applies.

In the object range-finder system two central adjustable range-nder mirrors are used. They are placed just anterior to the center stereoscopic adapter mirrors and are in the extended optical axis of the camera lens. These said mirrors may be of the split image type or the superimposed image type, the former saving space and allowing less horizontal dimension of the lateral rangender mirrors (preferably synonymous with the lateral mirrors of the stereoscopic adapter system) Housing apertures are of course arranged accordingly to accommodate these same camera lens angles and the mirror sizes laterally. Adjustable masks for the medial sides of the anterior apertures of the lateral housings are provided. Each mask is set into the aperture to such a distance as to approximate the medial edge of the useful eld of lens horizontal angle of view. This medial edge is the same for all lenses relative to the lateral mirror position of rotation and therefore must be adjustable for each rotation of the lateral mirror to keep at this edge. This is done to prevent center overlapping of stereoscopic images. Each mask is synchronized with its lateral mirrors rotation to keep at the edge of said angle of view and thus to move medially as the mirror rotates medially and laterally as the mirror rotates laterally.

No change is needed as the lateral housings separate; only as the lateral mirrors rotate. The only exception to this is one in which an initial adjustment separate from lateral mirror rotation may be made to mask some of the excessively overlapping stereoscopic image rays encountered with lenses having large apertures. The adjustment here is relative to the lens aperture, after which setting, the previously described synchronization of the lateral mirror rotation to th mask applies. l

fir-,accese In ithe object frange-*finder* :system two central adustable 'frange-iinder mirrors are' `used. 'They are placed just anterior to the center :stereoscopic fadapter'mirrors-fand are iin the extended optical 4axis-of the camera lens.. Thesesaid mirrors lmay 'the latter 'range-Huder system vis used the `more posterior mirror 'is equally reflecting `and transmitting and the more anterior one is totally reecting. `Both mirrors are preferably front 'surfaced-as are 'allniirrorsin this invention. 'The -center range-lnder mirror anterior edges are A'placed posterior to-theanterior -edges -of the 'lateralrange--nder mirrors by a 'distance l sufficient '-'to prevent loss Voftlfie dbjectfreectien into` said center mirrors 'from 4said la'teral ones at max-imum angul'ation "ci lateral ones in adjustmerit 'for any given `lens-angle of View lor object distance or any desired stereoscopic base. And

Iconversely, the lateral range-nder mirrors must e lbe of such size as to provide object rays to the center'mirrors respectively under the said'conditions. v A

The lateral range-finder lmirrors are synchro nousw'ith, or preierably'identical with the lateral mirrors o'f the-stereoscopic adapter System. It is der -toprovideimoremdy superimposition oi the camera object with that viewed -by the vpicture taker (observer). Also the lateralniirrorsareto `:befused' thus'if the range-'finder -is to allow ready observation in'theJoptieal-'axis of `the cameralens as 'is preferred.

Provision of 'an Jobject rangeentier system which vgives the lobserver a Atotal' field of view through it equivalent to thato'f the-camera lens total-angle of `view is contemplated.

IVIn this full angle 'of view` range-finder system there is no basic change,'exc'ept inviewing, from that just described. The center v`range-iinder mirrors must provide adequate dimensionsasalso must the 'lateral range-finder mirrors (preferably 'identical With'the lateral mirrors -o the stereoscopic picture-taker optical system), in orderto The 'said lspecial stereoscopic -viewing arrangement includes the use of polarizirrgvdevices to planepolarize oppositely thestereoscopic image u rays coming 'from-thetwo Iateral mirrors respectively towards the 'twocentral range-iiner mirrors. These polarized 'rays are v"carried into the optical axis of the-camera lens briefly in a posterior direction through a lens system which is 'fo- 5';

cused preferably by means synchronizing it' to Vthefcamera lens focusing, and then thepolarized rays are deflected superiorly to apolarizing screen (transmitting preferably) 'wherethe stereoscopic images are focused superimposed upontheescreen 75 -system which now acts vby proper adjustment of 'the range-:finder mir- 'rors'ior that particular object. The stereoscopic .oppcsitely 'plane-polarized images can be Viewed -erectlyf-on this polarizing screen through lsuitable polarizing -analyzers arranged to coincide with therespec'tive polarizers on that same side. One of the polarizing analyzers has preferablya small center area non-polarizing so that double images are appreciated by this eye for that varea View of `the superimposed images. This allows accurate super-imposition Iof the stereoscopic 'images *through this small .central-area- 'while the'restsof the images `can be 'received vin full stereoscopic relationship by both eyes of the observer. This 'central area lacking polarization may be replaced by'a polarizing area .as desired yfor special stereoscopic work where vobject range-iinding has already been done.

More particularly, a-system of polarizing analyzers "for VYobtaining :enlarged .concise images' of the polarizing screens stereoscopic images is presented. This system comprises an equally reecting and transmitting front surfacedl mirror near the polarizing screen which reflects rays ffrom the screen 'at right angles to the optical axis to a completely reecting mirror, which "directs therays through the polarizinganalyzer and a magnifying lens to the '.observers eye-on that side.

Another completely reflecting mirror is placed behind the previously 'dscribed 'equally reecting 1 transmitting mirror 1to receive the transmitted lrays which are then reflected laterally to another 'completely reflecting mirror and thence through lthe polarizing analyzer and a magnifying lens to the fobservers eye -on that side.

-These magnifying lenses, polarizing analyzers, and mirrors nearest to 'them are adjustable medio-laterally for Idi'ilerent interpupillary distances of diierent observers eyes by suitable means. v

in order properly to mask the angle o'f view 'of the observer to coincide with that oi the camera lens angle of View, adjustable masking of the polarizing `screen is provided.

In the previously described polarizing object rauge-iinder and viewing system, instead of a polarizing screen to intercept the polarized, erectly vviewed'real images, for viewing by the observer perpendicularly towards the optical a-xis of the camera lens, an optical system providing polarized erectly viewed virtual images vis `proposed. Inltliis said system there is no essential/change from the previously described polarizing system except for the said substitution. Any optical system providing said erect virtual image-.can be utilized in lieu thereof. It is preferable, however, to use some system providing a wide angle of view. Thus an inverted telescopic system is preferred.

If the observers line view -is parallel to the optical axis, an inverted Galilean, or terrestrial -te'lescopiceoptical system may be used; or if his lvi'ew -is perpendicular towards the optical ax-is,

ian inverted astronomical type would be preferred to keep the image erect to the observer. The same method of polarizing the respective image rays of light pertains and the same type 'of mirror inter-position asis convenient to transpose the axisto the level of the observers eyes is to be used. The vbinocular polarizing analyzer system has its magnifying vlenses replaced by the appropriate part'oflthe invertedl telescopic -as-'oculars The more anterior part of said telescopic system is then synchronized with the focusing of the camera lens in order to provide an image always focused on the desired object.

The problem of whether the observer is to do his viewing in a line perpendicular to the optical axis of the camera lens (vertically), or whether he is to do it parallel to said axis (horizontally), resolves itself into a consideration of whether the particular optical system used for presenting an image to the observers eyes gives an erect or an inverted image, the former having to be viewed horizontally and the latter vertically. Thus, this problem is easily solved as desired with commonly known optical systems for this purpose. No particular preference is made in this invention, various types being described.

In the view iinder system which is aligned in the extended optical axis of the camera lens to prevent parallax, the range-finder central mirrors and their image rays may instead of including the whole angle of view, provide merely the center of the eld of view especially with wide angle-lenses.

The center range-finder mirrors instead of being supported by view-obstructing rods, preferably are transparent and large enough to cover the whole iinder angle, except for only a central small viewing angle area of their surfaces provided with means of reection for use as rangender mirrors. This would allow unobstructed passage of light around the central small viewing angle made opaque antero-posteriorly by the means of providing reflection in the rangending system, and this unobstructed light would t comprise the periphery of the ileld of view of the observer, corresponding to the limits vof the peripheral eld of view of the camera.

This peripheral view comes directly in along the optical axis (undeiiected) of the camera lens through the anterior viewing aperture of the center-housing and it is supplemented by the central part of the eld of view from the central range-finder mirrors after which it is deflected superiorly by an interposed mirror to another one at the level of the obsevers eye whence it is re-l flected posteriorly into his eye. An inverted (or even an opposite type to give magnified images) telescopic lens system (terrestrial for horizontal and astronomical for vertical viewing) may be interposed around the last mentioned mirrors for more convenient image size. The anterior aperture of the viewing system in the anterior part of the centralstationary housing provides means for changing the rectan-gular field of view of the observer accordingly to that of the camera. This may be done by a series of masks for the aperture, or by an adjustable mask capable of constricion in meridians perpendicular to the four sides of the rectangle, or by a xed mask capable of being placed at varying distances from the observers eye.

An adjustment system mechanically arranged for accurate alignment axially of the camera lens and the stereoscopic adapter is presented.

This system is a simple one for adjusting the one relative to the other in directions mediolaterally, supero-inferorly, or antero-posteriorly.

superimposed upon the said adjustment system for axially aligning the camera lens into the stereoscopic adapter central housing posterior aperture is a simple entero-posterior adjusting system allowing free antero-posterior movement of the camera box and image plane relative to thelens upon the antero-posterior adjustment arm of the said lens axial adjustment system. This latter camera box antero-posterior adjusment relative to the camera lens is important in its maintaining of the camera lens in the posterior aperture of the central housing, for this prevents movement of the lens away from the central mirrors of the stereoscopic picure taking optical system with consequent loss of the more peripheral rays of light from the object field.

Except for the camera lens aligning aperture, the lateral housing anterior apertures (excepting the medial masks), the viewing aperture in the anterior part of the center housing, and the observing aperture in the superior side of the center housing, the stereoscopic adapter allows no en trance of light nor exit of light. This is obtained by use of a bellows arrangement between the side housings and the central housing, and rm opaque material covering all other areas except the above mentioned apertures,

In summary, that which is set forth, in main, is briefly a stereoscopic adapter providing:

1. A variable stereoscopic base.

2. A variable stereoscopic point of convergence.

3. A xed stereoscopic base with a xed stereoscopic point of convergence.

4. A variable stereoscopic point of convergence with a variable stereoscopic base.

5. A xed stereoscopic point of convergence with a variable stereoscopic base.

6. A variable stereoscopic point of convergence with a xed stereoscopic base.

'7. A variable separation of stereoscopic camera images, including superimposition.

8. Accurate separation of stereoscopic images for all diierent focal length lenses in proportion to their lens horizontal angle of View.

9. Prevention of stereoscopic image medial overlap, for all aperture lenses, and prevention of lateral restriction of stereoscopic images.

10. Maintained separation of images for varying object distances.

11. Maintained separation of stereoscopic images for varying object distances with all focal length lenses.

12. Maintained separation of stereoscopic images for varying object distances with all focal length lenses, while maintaining simultaneously a variable stereoscopic base.

13. Maintained camera lens position in its aperture at the stereoscopic picture taker while focusing the stereoscopic images by variation of the camera film image plane relative to the lens position.

14. A variable object field angle of View of the observer equal to that of the camera lens total angle of view. y

15. A variable object field angle of view of the observer exactlyvsuperimposed upon that of the camera lens total angle of view, thus allowing no parallax.

16. A variable object eld angle of View of the observer exactly superimposed upon that of the camera lens total angle of View, thus allowing no parallax, and including an inverted telescopic viewing optical system.

17. An object range-finder optical system of which the stereoscopic adapter optical systems lateral mirrors provide an integral part.

18. An object range-iinder optical system whose lateral mirrors are capable of synchronous movement with the lateral mirrors of the stereoscopic adapter's optical system.

19. An object range-finder optical system viewed coincidently with the extended optical stereoscopic Eli axiso'f the' calmer-a lens, allowing?" no parallaxf between them".

20'i Ani' ob'ject range-finder optical systeiii viewedf as a central supplementi to'- the-1 totai' field* offviewot the'fobjecteld angle ofview-'of' the'A observer; coincident with` that of' the' camera' lens tota-l2 angle of' view.

21-;An'obe'ct viewer .andi rangeefnder coni'-A binedE optic'aisy'steri includinga magnifying p'able; ofi. accurate adjustment t'o tlie' lens' angle'- off View for maintained visual'` adjustmenti of accurately.' separated stereoscopic] imagesl 232 An objectrangeiinderf'andfuillstereoseopic depth, non-parallactic; viewingf systexiif. fon accioratelob'ject' rangelflnding' forlallLooiect distancesf stereoscopic bases. and? diieren'leiis" angles of view,A with sixiiultaneousy fili stereoscopic depth Viewingk. equivalentin! image? and*- an'gleto) those stereoscopic iinagesforietl Uyi the minimi lens.

25. An integratod-nonparallctic 'olijeetfvieweii' and rangesnnder optical: system. for: accurate visual adjustment ot'thestereoscopicihia'ge sepa`- ration' aii'cl'depth',` and thleri focus; while varying the stereosmpiobase'witiiavariying stereo.'J seo'pic point oi? convergence to? maintain: a xed Silesbpolalllgl 26. An integrated nonhparallaotieobiectvlewer andi range-nde'rf optioar system: fox'accurate visualfadju'stnrent-'or-:the stereoscopic image'sepaa ration .ancl depth"y andltlioilensifows; I while' Varye ing'tli'e stereoscopic; with ava.mf1irrgster'e'o scopic point-oi convergence" t'olvary the:` ster-co1' scopic angle.

27. An integrate'crnon-paraliactiwobject viewerv and range-finder optical system for' accurate visual adjustment off' the' stereoscopic.' image separation and depth;- and the lens-focus; while maintaining" the' stereoscopic base' static and'y varying the stereoscopiopoiitofl convergence;

285 Eliminationfof'undesired extraneous' ligfnt betwee'nhousing's. andprovidingaveriable or static separation ofi steife'oscopic imagesl by" accurate visual adjustment' ofi an'. in'tegiiatedi non;par-aliv lactic object range-finder and viewer optical-sys*-A t'em mechanically! v'vith'.l the variable stereoscopic base', the variable stereoscopic point;` oi converJ gence, and the variable lenses focusiiigs and angles of view fora giverriobiect'.

For further comprehension of the?inventionv andi of the objects-aridl adventages;\thereoftref-` erence will be had tothe following description and accompanying' drawings'. andi to'vthe appended' claims in which the; various-novelfea tures of' the invent-ion are# more2 parteilarlylset forth.

In the accompanying drawings" wliiclt'. are: a material-pai't oft thi'sdisclosur'et Fig. 1 s'a fragmentary perspectivefview of the stereoscopic adapter-showing the housings and mirror systemsv in accordance with the principal embodiment illustrating this4 invention, and viewed' fromA the'- front, obliquel'y down'.'

Fig. 2 is a fragmentary''perspectiveiviewfofv the stereoscopic adapter' showing the' housings and mirror systems in' aec'ordanoel with'- this inven- 12. tion; and viewed fromithefront.; oblioueiyfdown Italsoshow's the medialmasking of the-lateral housing anterior apertures' an'd'. a viewing box',- but is without the central housings anterior aperture viewing mask.

' trail housing' showing? the relation ofits optical.`

elements and theV path-of therays' of light tothe-I obs erver-s e'ye:

Figi 'Iissimila'rto Fig; 6, but less detailed' a'n'd snowing onlythei optical elements of thevie'wer andran'geeinder-'systein of the central.housing.v

Fig; 8 i'sz ai diagrammatic' horizontal sectional view oi` the' center housing: taken at a` line'S-r' inl Fig. 6; aridshowing the. course ofth'e lightf rays in the periphery of the viewereldfro'xn ,th'e anterior aperture of' the' center" housing', in

.Fi'g 9') ilsa' diagrammatic' perspective vie'w of! the' elements for adjusting. the' camera' 1ens'i'ntoaX-i'al alignment' with the stereoscopic adapter" a'tits'; center' 'housing posterior' aperture;

Fig. 1Uis-aper'spective view 'of' one of a'l pali" of' adjustable clamps shown-in position in'V Fig. 2'21 Fig; 11' is`- aperspective-view of av movingplat'efor'mfr'use in anteroposterior adfust'rnentof-Tthe camerajbox relative tothe' lens position; to be'` usedw'lth the'structureof Figs; llt- 10.

Fig'. 12`is' a diagrammatic' view'of one-half of the oppositeiy' pairecl racks with gears, controlling and' leading from` one" lateral mirror rod.

Fig; 13'A is a" diagrammatic perspective view of'` the" mechanical' system synchronizing' the'late'r'al" m'rror'move'rne'nt' to that' of' the lateral housing anterior aperture medially masking curtain.

Fig. 1'4' is the other half of the oppositeiy. pairedrack and gear system, for the other lateral mirror.

Fig. 15- is the diagrammatic sketch of the oppositely. paired rack and gear systemusod insepA aratingv the lateral housings, with` some of the immediategearings--leading to it and away from it.A

liig, 16 is. the diagrammatic system showingone method for` the synchronizing n'iechanismae-L tween-the lateralf mirror gears-andthe lens focusing gears asia'djusted' bythe-housing separa-f tion-.ratio gears.v

Fig. 17f shows' the lens focus:- regulated ratio4 gearing?. between. the system: providing' adjust-v mentof-v the lateral mirrors' by? synchronization with' the'I housing: separation' adjustment.

Fig. 18 is a. diagrammatic view of the mechan`-r ioalelements immediately 'synchronized with; the lenoft'lousing-Y gearing;

Fig. 1.91 is'. a diagrammaticperspective view' or the main elements ofi the; various. mechanical sohroiz'aitois.' between" plflS 'fn ocidalie with the main" embodiment' of this invention.

Fig; 20 is a diagrammatic perspect'ive'-view'I of the mechanical system allowing camera' lens fo'- cusi'ng' with proportionate an'g-ulation'. o'iA the'- lait# 'e'rall`v mirrorsto` obtain a valr-i'able' stereoscopic point-of convergence, regardlessv of the' separation, passive or active, ofA the' lateral housings;

Fig".- 21 i's a fragmentary perspectivel View' of the housings for the optical systems to show the relation between the housings and their related mechanical system which are more exhaustively shown in Fig. 19.

Fig. 22 is a perspective view from above obliquely of the preferred embodiment of this invention showing the working relationships of its main units.

Fig. 23 is similar to Fig. 22 but its perspective is from below obliquely.

The stereoscopic adapter in accordance with this invention includes a central stationary housing I0, having a posterior central aperture (Fig. 3) for engaging upon the lens 24 of a camera |2 (Fig. 5). The housing has open sides I3 laterally, an anterior viewing aperture 33, the aforementioned posterior lens engaging aperture and a superior observing aperture 3|. The other surfaces are lightproof.

Two central mirrors |4 (Fig. 4) at right angles to each other, with their reiiecting surfaces directed posteriorly and laterally are xedly mounted along the optical axis of the camera line 24 within said housing |0 with their contacting edges arranged to extend vertically.

Side housings (lateral housings) ||i-|t` are disposed to the sides of the central housing I9. These side housings have their medial sides |1 open. The adjacent open sides |1 and |3 of the lateral housings and center housing respectively are connected together by bellows 49 (Fig. 2) or a similar light opaque extensible arrangement for preventing external 'light from entering these areas'extraneously. A 1" These side housings I5 are associated with means (Figs. and 2l) for simultaneously adjusting them `towards or away from the central housing I0. More particularly one of the side housings i6 is provided with a rack. |26 which is parallel and posterior to another rack |24.

These racks |26 and |24 are maintained laterally movable -in parallel relationship, on a supporting base plate which is xedly attached to the central housing I0. This plate 20 extends beneath the side housings I6, for the full extent of the travel of the side housings.

The plate 20 is provided with guides through which Ithe racks |28 and |24 are kept parallel and moving perpendicularly to the vertical plane of the optical axis of the camera lens 24.

A rod (Fig. '7) is rotatively mounted perpendicularly and extending inferiorly through the base plate 20. This rod is the axle for a system cf gears and racks intimately related to the function of moving the lateral housings I5 away from and towards the center one |0. The most inferior end of the rod is provided with a handle |23 as a, means for manual turning. The most superior end of the rod is provided with a gear for simultaneously meshing with the opposed racks |24 andl |25 in order to adjust the lateral housings I6 separation. The intermediate portion of the rod is provided with gears H9, ||1, and |41 for synchronous adjustment respectively of the angles of the lateral mirrors 25 angle, the ratio lever |31 between the lens focusing system. and the lateral mirror angulation system, Fig. 16, and lastly the lens focus (Fig. 19). Gears H9, ||1 and |41 mesh respectively with the rack |59, rack |2| and rack 48, for the above described purposes.

- Two side mirrors (lateral mirrors) 25 (Fig. 1) are mounted within said side housings I6 and are set with their reflecting surfaces anteriorly and medially directed to the optical axis of the Y mirror 25.

14 camera lens 24 (Fig. 5) and are placedlaterally to the said two center mirrors I4.

These two lateral mirrors 25 usually form an angle equal to or less than 45 degrees to the optical axis of the lens 24 or the camera |2 (Fig. 5). These side mirrors 25 are mounted upon vertical rods 25 Fig. 8 which are rotatably mounted in the lateral housings i6. These side mirrors 25 are mounted at their most posterior edges -to these vertical rods 26. By adjusting the pointers 21 (Fig` 2) it is possible to change the angles of the side mirrors 25 and by consulting the scales 28 it is possible to set the side mirrors 25 to the same angular positions.

A mechanical means Figs. 12 and 14, is provided for simultaneously adjusting the lateral mirrors 25 to the same angular positions after the initial manual adjustment for that particular lens has been madl and a gear |05 is in mesh with a rack |01 for this purpose. l

More particularly, the rotatable rods 2B, upo which are iixedly mounted the lateral mirrors 25, have at their inferior ends systems of gears providing graded variable movement of said lateral mirrors 25 translated from a constant rate of movement of rack |01. Specifically, one rod 28 (Fig. 14) has at its inferior end a gear 85 which is eccentric and meshes with another eccentric gear 84 on rod 82. To rod 82 is xedly attached gear 83 which meshes with gear 8| which through rod turns gear |04. Gear |04 meshes with rack |01 and thus transmits indirectly any motion from rack |01 to rod 26 and In order to cause opposite rotation of the two mirrors 25 on their respective rods 25, in the gear system of the other side gears 8| and 83 and rod 82 are omitted and eccentric gear 84 is flxedly mounted on rod 82 with which it turns and meshes with eccentric gear 8-5 (Figs. l2 and Racks |01 and |08 Fig. 9 are respectively paired racks opposed to each other, moving oppositely and lying in parallel axes perpendicular to the vertical plane of the optical axis 2|. The

l racks |01 have a ridge |44 which iits into a groove |09 in the racks |08. The adjustment is such that movement of rack |08 carries rack |91 exactly with it, but movement of rack |01 primarily does not move rack |08. Thus turning of the gear |05, which meshes with rack |01, provides movement of rack |01 and consequent rotation of rod 26 Without movement of the rack |08 whereas turning of a gear |06 which meshes with rack |08 moves both racks |08 and |01.

Synchronization of the lateral mirror angle adjustment can be done manually by the turning of the knob |22 which is fixedly attached to the rotatable rod H2 on which is secured gear |05.

When gear |05 is turned by rod ||2 by the knob |22, it simultaneously moves oppositely the racks |01 without moving racks |08.

An adjustable medial mask for the anterior aperture of the lateral housings is provided, (Figs. 19 and 13). This mask is in the form of a vertically rigid and horizontally exible curtain 39. This curtain 39 is located medially of a line parallel to the optical axis of the camera lens 24 and going past the most posterior edge of the lateral mirror 25 and is just inside the plane of the front surface of the anterior aperture of the lateral housing.

Rotation of rod 38 and gear 50 Fig. l() guides the curtain 39 by end rods 31 and small guides 59, through slots 51 parallel with the lateral housing antero-medial angle surfaces.

conveniently, especially with use of telephoto camera lenses, and thus, for example elements 41 and 48 (Fig. 7) would be reversed in order to give this effect.

This system is one of two non-parallactic ones, and in this case viewing through the range-finder mirrors and 38 and the aperture 33 all in the optical axis (extended) of the camera lens 24, prevents any deviation of the observers images from those of the camera due to parallax.

This polarizer 309 may be replaced readily by suitable means with another polarizer with no central aperture, as desired for complete stereoscopic depth appreciation by the observer in viewing at a fixed stereoscopic point of convergence.

The polarizing analyzers 308 and 399 have their polarizing planes respectively parallel in the viewed optical axis with those of polarizers 30| and 300, thus affording the images of those respective sides to the appropriate observing eye for full stereoscopic depth appreciation.

Masking of screen 303 variably by suitable means for different lens angles of View provides the observers angle of view equal and coincident to that of the camera lens.

Polarizing screen focusing lens synchronization:

In order to keep in focus the images of an object at varying distances, the lens system 302 from the optical polarizing viewing and rangefinding system (Fig. 24) which focuses the polarized rays of light going to the polarizing screen 303 must be adjustable. This adjustment is best made synchronously with the camera lens focusing system.

Thus, as in Fig. 25, the rack 453 which imparts movement to gear |81 and thus to the rest of the camera lens focusing movement, may be extended to move a similar lens focusing system for lens 302,by engaging with gear 454 which turns rod 455 and finally thru two right angled, leveled gears 455e and 455b thus turns eccentric gear S which then turns eccentric gear 451 to give a graded variable movement satisfactory for focusing the lens 302 antero-posteriorly, shown by arrow line 3|4 when gear 451 turns rod 458 and gear 459 to move antero-posteriorly rack 460, to which lens 302 is fixed.

Various mechanical synchronizations are provided between the angle of lateral mirror 25 and the adjustment of masking curtain 39 adjustment, the lateral separation of housings I6, and the lens 24 or |95 focus, for use with the Visual range-finder and viewer optical system as the only criterion as to satisfactory stereoscopic images. A brief description of these systems and their functions is interposed here.

There are three basic systems for alternate use as desired for different stereoscopic picture taking purposes:

The first system, more easily designated as the lens-mirror system, is that for varying the stereoscopic angle in proportion to the changing object distance by changing the lateral mirrors 25 angle according to the object distance, while keeping the lens 24 in focus and the lateral housings l5 fixed in separation. (In other words, to maintain a fixed stereoscopic basic separation of the lateral housings I6 with a changing object distance.)

The second system, more easily designated as the housing-mirror system, is that for varying the stereoscopic angle with a fixed object distance by maintaining a static lens 24 focus on the object while the lateral housings I6 change in separation and the lateral mirrors 25 change lll angle to maintain the same separation of stereoscopic camera images.

A third system of synchronization, more easily designated as the lens-mirror-housing system, is that one which combines the functions of the aforementioned first and second systems, the lens-mirror and the housing-mirror systems respectively. This combination is so synchronized (Figs. 19 and 20) as to allow the use of the two component basic systems simultaneously as well as separately.

Integral to these basic systems of mechanical synchronization is the primary setting up of a lens focusingv mechanism, Fig. 18, which allows translation of an even motion from or to any one of the three said systems into a graded variable movement suitable for the focusing of lens 24, Fig. 18, by rotating of the lens barrel in the camera box |2 to obtain a relative anteroposterior movement, by simple linear anteroposterior adjustment. The graded variable movement for focusing either lens type is one moving slowly for an object distance adjustment nearer rom infinity and moving quickly for an object moving the same distance but at a range much closer to the camera lens. Such a variable system can be set up using eccentric gears |89 and |90 between two round gears |92 and |81, Fig. 18.

A rod II by means of a gear |92 may turn a screw-thread type of lens barrel provided with gear |93 (Fig. 18) and thus adjust the lens 24 in an antero-posterior direction. The rod |9| is rotated by the gear |90 in mesh with the gear |89. Rod |84 has mounted thereon the gears |ii|, |82, and |83, but can be disconnected from the gear by pulling on knob |86.

Referring to Figure 19 there are here shown the interconnections between the mechanisms for effecting conjoint movements of the side housings |6-I6 and the lateral mirror 25, between the lens 24 and the lateral mirror, and between the lens and the side housings.

Gear |82 meshes with rack |11 which is the connection of the lens gear system with the lever |54 (Fig. 1'1) providing changing ratio of movement between means for separating the housings I8 and the means for angularly moving lateral mirror 25 of the housing mirror system.

Gear |8| meshes with rack |32 which is the connection of the means for adjusting lens with the means for moving lateral mirror 25 in the lens-mirror system.

Gear |80 meshes with rack |48 and is the connection of the means for adjusting the lens with the means for separating housings change of the lens-housing system.

The lens-housing system is synchronized as follows:

The other two systems are adapted accordingly by letting gear |05 and knob |22 (Fig. 12) turn freely with racks |01, and pulling sleeve-lock |a apart by knob |86a so that rotation of gear ||4 will have no effect on gear 489, thus serving to neutralize the effects of the lens-housing system on the lens-mirror system; and disengaging -lever |10 (Figs. 17 and 19) from notch |14 in rack |11 to release it by engaging its notch |12 by block |15 pushed up by knob |19 and rod |18 to lock therethrough stable guide |13 after notch |12 is superimposed over block |15 by turning knob |69 and thus rod |52 and gear |5| are caused to engage and move rack |50 and lever |10 until said notch |12 is over said block |15 and then spring |1| may pull the lever |10 and rack |11 together. This provides a 1:1 ratio of movement of the lateral mirrors 25.

movement between the change of separation of' the housings I and the angular movement of-'the lateral mirror 25, thus neutralizing any angular Sleeve lock |85 is then pushed together so that rack |48 thru gear |80 may turn rod |84 for lens-focusing. Then the lens-housing system is operated by turning knob |23 which turns rod (Figs. 15 and 19). Rod turns gear |25 and moves oppositely and to or from the side, the opposed racks |24 and |26 Which are Xed to the lateral housings I0 respectively and which carry the lateral mirrors 25.

At the same time gear ||9 is turned and this engaging with rack |59 (Figs. 19 and 25) moves it through the lens ratio lever system, against gear |62 which turns rod I3 and gear |06. Gear |06 is meshed with the opposed racks |08 and moves them oppositely, in the same respective directions as racks |24 and |26 were moved.

Racks |08 carry racks |01 with them and would rotate the gears |04 and thus, as previously described, the rods 26 and the lateral mirrors 25, but the lateral housings i6 carrying the lateral mirrors 25 are separating at the same speed as the racks |01 and no turning of gears |04 or the lateral mirrors results.

Thus the effect is achieved of no lateral mirrors 25 rotation as the housings I6 are separated.

To keep the lens in focus, the gear |41 is meshed with rack |48y which turns gear |80 (Figs. 18 and 19) and now that the knob |86 has pushed the sleeve-lock (like a Watch-stem) |85 onto rod |84, rod |84 tur-ns as a unit with gear |80 synchronizing the lens focus through the previously described lens focusing mechanism.

Lens-mirror-housmg system (LM-H system) The combined lens-mirror and housing-mirror systems are functionally so closely related that for the sake of clarity they shalll be considered jointly in description of their main mechanical action; the separation of their individual functions being brought out later as the lensmirror and housing-mirror systems respectively.

For use of this combined LlVl-H system the other system, namely that of the lens-housing system, is thrown out of gear by pulling on handle 180 (Figs. 1S and 19) thus disengaging the clutch, or sleeve-lock |85 to free rod |84 from the rotation of gear |80 so that gear- |80l no longer transmits rotation thereto from the lens-housing system. Sleeve-lock |85a is engaged by pushing up knob |86a so that rodl 4|0 rotates as a unit When gear ||4 does. The lever |10 (Figs. 17 and 19) is disengaged from the block |15, and by turning knob |68 it is made to engage its knob |16 into notch |14 totransmit variable lens ratio movement on lever |54 according to the lens focus.

The difference between the rates of movement in the same direction of the grooved-together paired racks |01 and |08 respectively is indicated by the ratio levers 401 (Figs. 19 and 20) movement. The movement of this lever is determined by the difference between the movement or the rack |01 superimposed upon rack 08 and determines the amount of'angular movement of the lateral mirror that is to be associated with change oflens focus.

Racks |01 are in mesh With gear 42| which turns and moves in mechanical sequence rod420, gear 433, rack 434, gear 435, rod 4|3, eccentric gears 4| |St and 4|2a, rod 420e, gear 403 and rack 40|. Racks |08 are meshed with gear 422 which 20) turns to-move in mechanical' sequence rod 4 I 9, gear 432, rack- 43I, gear 430, rod 4|3', eccentric gears 4H andv 4|2, rod 4|9a, gear 402 and rack L200. Racks |01 are thus also connected toa mechanical system, including two eccentric gears, imparting motion to rack 40|.

These said eccentric gears are used to change the movement oi racks |01l and |08, respectively, into a graded variable movement transmitted to racks 40| and 400" respectively. This graded variable movement isl designed to compensate for the decreasing angular rotationV of lever 401 as the oppositely moving racks |01 and |08,y and therefore racks 40| and 400 respectively', are

.moved farther apart laterally. Thus, for any given distance of movement of a rack |01 or |08 there is a directly proportionate angular rotation of lever 401.

Racks 460 and 40| (Figs. 19 and 20) thus are parallel and move oppositely laterally. They are separated parallel by adequate distance for inserting a lever 401 between them. This lever 401 is attached pivotally to racks 400 and' 40| at points 418, and by end pieces 405 and 406, re-

spectively. The purpose of these end pieces is to allow fixed rods pins 4|4 and 4|5, respectively,

(Fig. 20) to be inserted and to ride in slots 4||3` of lever 401, so that as the lever 401 changes position its effective length will not interfere with this change'. Lever 401 is rotatably mounted at its center 425 on rack 408 which in turn has a pair of fixed pins 426 riding in grooves 423 of the xed guide bar 404; This rack 408 then moves parallel to racks |01 and |08 on the guide bar` 404 and causes any difference in the rate of movement between the opposed racks 400 and 40| to be transmitted to gear 409 with which rack 408 is in mesh. Gear 409 then rotates accordingly and turns rod 4|0 and gear 4|4 which is in mesh with rack |42.

Any movement of gear ||4 is transmitted to rack |42 which then moves the housing separation ratio lever |31 and according to the ratio effects a corresponding movement of rack |32. Rack |32 turns gear |8| and thus the mechanical system leading to the focusing of the lens.

In explanation of said lever-rack |31, this lever has as its fulcrum` a small gear |40 on rod 99. Rotation of gear ||6 by' rack |2| reciprocation (Figs. 16 and 19), and initially through movement of knob |23, turns said gear |40 which changes the position of lever |31 about its fulcrum, gear |40. Thus the rotation of gear |40 depends on the position of separation of the lateral housings I6 and thus the ratio of movement between racks |42 and |32 depends on thev lateral housings separation.

Guide frame |38 (Fig. 16) provides support for rod 09 andspring |45 keeps the gear |40 snugly against4 the lever-rack |31.

spectively. Rack |32 then turns gear |8| which,

synchronizes the lens focus through the previously described mechanism.

Lens-mirror system The lens-mirror system being engaged by pushing-in knob |852' so-that gear ||4 is synchronized with gear 409 thru clutch the housing mirror Slots |34V and |33 provide means for changing the lever |31 ratio system being static by locking knob |23 (the lens ratio to the housing-mirror system may be either at a static 1:1 or variable, preferably the latter by disengaging block |15 from notch |12 in lever |10 so that spring |1| (Fig. 17) may pull it down onto rack |11 and knob |68 may be turned to engage tip |16 into notch |14 to lock it there and allow variable ratio of movement in the housingmirror system when it is again set in use), and the lens-housing system being disengaged as described previously through lock-sleeve |85, the lens-mirror system functions as follows:

Turning knob |22 rotates rod ||2 and gear |05 which is engaged with racks |01 and moves them simultaneously oppositely, turning gears |04 which as previously described, ilnally turn rods 26 and the lateral mirrors oppositely angularly. Racks |01 move on racks |08 without causing any movement of racks |08. Since rack |01 now moves without any movement of rack |08, the focusing of the lens must then vary with this movement of rack |01 which represents a corresponding change of lateral mirrors angular movement.

Housing-mirror system The lens-mirror system being passive (no active movement effected through knob |22 which is preferably left completely free and passive) and the lens-housing system being disengaged as noted previously through locking sleeve |85, and the lens-ratio set at variable for the housing-mirror system, and the lens mirror system either engaged or disengaged through locking sleeve |8511; the housing-mirror system functions as follows:

Turning knob I 23 rotates rod I which rotates gears |41, ||1, ||8 and |25. Gear |41 moves rack |48 which is now ineffective in focusing the lens because its connection is disengaged at clutch |85. Gear ||1 moves rack |2| which turns gear ||6, rod 99 and gear |40. Gear |40 is meshed with and moves the housing-ratio lever rack |31 to regulate the ratio of mirrors 25 angulation to lens focusing accordingly as the lateral housings i6 separation varies.

Gear ||9 moves rack |59 which moves lens ratio lever rack |54 and this lever corresponding to the lens focus given ratio accordingly moves rack |6| which is in mesh with gear |62. Gear |62 moves rod ||3 which similarly turns gear |06 which meshes with racks |08 and moves them oppositely in parallel relationship carrying racks |01 with them.

There is no focusing of the lens for there is no diiierence in the rate of movement of racks |01 and |08.

There isrotation of the lateral mirrors 25 depending upon the difference in rate of movement of the racks |01 (here moving the same as racks |08) and racks |24 and |26 moving in the same respective directions. This result occurs since the racks |24 and |26 carry the lateral housings i6 and their mirrors 25 respectively in opposite directions and the movement of the racks |01 is corresponding. Racks |01 will not be able to rotate the lateral mirrors 25 through gears |04 and l and rod 26 unless the speed of movement of these said housing Aseparation racks |24 and |26 differs from that ofthe mirror rotating racks 01. Here said difference in speed depends upon the lens ratio lever rack |54 and thus primarily upon the lens focus, as the lateral housings I6 are moved apart, and the effect with the lens ratio lever thus variably set, is to maintain the same stereoscopic point of convergence by appropriate angular movement of the lateral mirror 25 re'- gardless of the separation of the housings |6.

The function of the rack-lever |54 is to allow variable lever ratios between the movement of the housings I6 and angular movement of the mirrors 25. This is accomplished by a small gear |53 in mesh with the rack |55 of the lever |54. The lever |54 has as its fulcrum the small gear |53 on rod |52. Rotation of gear |53 changes the position of lever |54 upon this gear |53 which provides the fulcrum for lever |54. Rod |52 is turned by gear |5| which is turned by rack |50 (Figs. 1'7 and 19). Rack |50 is subject in this system to being engaged to rack |11 through lever |10 by its knob or tip |16 into notch |14. Rack |11 is moved by gear |82 which is subject to the turning of rod |84 and thus functions to the focus of the lens and its mechanical system as described previously.

Rod |52 can be turned by knob |69 to engage either block |15 into notch |12 or tip |16 into notch |14 as desired according to the system used.

Thus the position of gear |53 on rack |55 of lever |54 depends on the focus of the lens at that moment and thus the ratio movement provided by lever |54 between rack |59 and rack |6| depends on the lens focus.

Guide box |65 provides support for rod |52 and spring |66 keeps the gear |53 iirmly against the rack |55 of lever |54. Slots |58 and |68 provide means for changing the lever |54 ratio without moving the racks |6| and |59 by turning gear |53. The wedge shape of lever |31 provides means of even more exactly maintaining the same relative positions of racks |58 and l6| as the point of fulcrum is changed by gear |53, thus moving lever |54 up or down by its rods |51 and |56 in slots |58 and |68 respectively; and also provides means of making a slight gradient increase in the ratio of the angular movement of the mirror as the separation ofthe lateral housings increases.

Rack |6| moving in its long axis then turns gear |62 which turns rod ||3 and turns gear |06. Gear |06 turns racks |08 which respectively carry racks |01 with them to turn gears |04 and thus the rods 26 and mirrors 25 through the previously described systems.

An adjustment system mechanically arranged for accurate axial alignment of the camera lens and the stereoscopic adapter optical systems is afforded (Fig. 9). The camera is mounted on section 20| of the uppermost bar by thumbscrew 2 l1 through hole 200. Section 202 of this bar rigidly supports part 20| on part 203 which is secured to part 205 of the right angled bar beneath by an adjustable clamp 204 such that anteroposterior adjustment as indicated by the arrow 2|8, may be made. Section 205 is fixed by a tripod or other support mounted through thread hole 206 and the extension 201 is opposed by bar 209 which is adjustable by variable clamp 208 to an intero-superior direction, as indicated by arrow 2|9.`

Section 2||` is attached to 209 and on it is mounted a plate 2|2 which has a slot 2|3 running laterally for its full length, through which slot screws pass from holes 2| 0 of plate 2|| to thread into holes 2|5 of plate 2|6 and provide variable movement of plate 2|2 between plates 2| and 2|'6 by movement of screws from holes 2|0 to 2|5 through slot 2|3 laterally, as indicated by the arrow 220.

Section 22| of plate 2|2 provides for attachment to the center housing I0 of the stereoscopic adapter through itsv base plate y2|] by bolting through holes v2|4 into the base plate 2|) at its center. Thus movement in all directions is possible to secure satisfactory alignment of the camera lens 24 with the stereoscopic adapter optical system thru aperture I I.

This said axial adjustment system for the camera lens, in order to provide easier means of antero-posterior movement of the camera boxes to permit a xed position of the lens relative to the stereoscopic picture taker, is `provided'with an alternative plate 225 (Fig. 11) for mounting upon section 20| by thumb screw 2 1 through hole 200. This system is a composite one allowing smooth and low friction antero-posterior movement of the camera box relative to section 20|. This said movement is accomplished by the movement of plate 228 on plate 225 by means of ball bearings 221 moving in grooves on Yone plate and fixed to the other plate by retainers (not shown) which does not restrain the rotation of these ball bearings. The camerabox Weight is centrally balanced upon this plate 228 for reasons of smoother movement by antero-posterior adjustment bar 229 and lateral adjustment bar 234 which provide holes 232 for fastening bar 23s to the camera box by a screw 233 similar to 2H, and bar 234 through holes 236 to plate 228 by screw 23|. This said composite plate allows simple antero-posterior movement lof camera box l2 as previously described. A binocularviewing box 31| (Fig. 22) serves as a housing for the mirror viewing system and allows viewing parallel tothe optical axis of the camera lens 24.

Exterior light is prevented from entering the housings of the stereoscopic adapter except at the anterior apertures of the lateral housings iE, the anterior aperture 33 of the center housing ID, and the observing aperture 3l in the superior side of the center housing I0. From the movable housings I6 medial apertures to the central housing lateral apertures, bellows 48 (Fig. 2) are placed to keep the external light out and the apertures I3 and Vl unobstructed. All otherfareas are covered by light opaque substances, preferably of firm consistency suitable to give the ap.. paratus permanent shape. A light shade extensible between the aperture I'l and the camera lens mount is provided 'to keep extraneous light from the apparatus at that point. tube with eye-pieces for viewing by the observer of the images from the superior viewing aperture 3| is preferred, and may be modified into the polarizing analyzer device for viewing polarized stereoscopic images asin the system previously described and illustrated.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent is:

l. A stereoscopic adapter, according to ne specication, comprising a central stationary housing having a posterior aperture for engaging upon a camera Ylens `and box in axial alignment and having open sides, said camera lens being maintained static in said posterior aperture and protectedfrom external. iight, two center picturetaking mirrors with planes at right angles to each other respectively 45 degrees to the optical axis of ie camera lens with their re'liecting' surfaces directed pcsteriorly andlaterallyfand fixedly mounted within said housing along the optical of the camera lens with their'contacting edges extending vertically, side 4housings open anteriorly and disposed laterally to said central housing and l'i'avingtheir medialsides open and A hooded in line with the correlated central housing operi sides, said medial sides being joined by a lightprooi variably extensible structure, mechanism including racks connected to said side housings and a in mesh with said racks for shitting said side 1housings with respect to the center housing, and means for preventing center overlap of stereoscopic picture images, including a mask at the medial side of each lateral housing anterior aperture, cach of said masks being adjustable over its correlated side housing front for said pur-pose and accor` ingly synchronized by means of said rack and gear mechanism with the lateral housing mirror angulation respectively, and alsoa-djustable for different camera lens apertures as desired, and two side picture-taking mirrors mounted on@ in each of said side heus-- ings and set with their reiiecting surfaces anteriorly and medially directed relative to the optical axis of said camera lens and placed with their posterior edges lateral to the contacting edges of said twc center picture taking mirrors and iol-ming an angle variable from a maximum of @i5 degrees to minimum of 0 degrees to the optical axis of said camera lens and means i`or varying the angles of said side mirrors separately and means for varying the angles oi said side mirrors simultaneously.

2. A stereoscopic adapter, according to the specification, comprising a central stationary housing having a posterior aperture for engaging upon a camera lens and box in axial alignment and having open sides, said camera lens being maintained static in said posterior aperture and protected from external light, two center picturetaking mirrors with planes at right angles to each other and respectively 45 degrees to the optical axis of the camera lens with their reflecting surfaces directed posteriorly and laterally and nxedly mounted within said housing along the optical axis of said camera lens with .their contacting edges extending vertically, side housings open anteriorly and disposed laterally to said central housing and having their medial sides open and in line with 'the correlated central housing open sides, said medial sides being joined by a light-proof variably extensible structure, and means for preventing center overlap oi stereoscopic picture images, including a mask at the medial side of each lateral housing anterior aperture, each of said masks beingl adjustable over its correlated side housingifront for said purpose and accordingly synchronized by means of a rack and gear device with the lateral housing mirror angulation respectively, and also adjustable for different camera lens apertures as desired, means for simultaneously adjusting said side housings towards and away from said central housing comprising racks connected to the side housings and an operating gear meshing with said racks, and two side-picture taking mirrors mounted one in each ofsaid side housings and set with their reilecting surfaces anteriorly and medially directed relative to the optical axis of said camera lens and placed with their posterior edges lateral to the contacting edges of said two center picture taking mirrors and forming an angle variable from a maximum of 45 degrees to a minimum of 0 degrees to the optical axis of said camera lens and means for varying the angles of said side mirrors separately and means for varying the angles of said side mirrors simultaneously, said last mentioned means having a part adapted `to coact with the said camera lens for synchronizing said varying of said side mirror 

